 1600s scientists observed cells Most did not understand what they saw  1838 – cell theory All things are made up of tiny units of matter called cells These cells divide and multiply They cause organisms to grow and mature Developed by Mathias Schleiden and Theodor Schwann

 Cell theory failed to explain plants and animal varieties  1800s theory of evolution was proposed  Jean-Baptiste de Lamarck found similarities in fossils and living organisms  Charles Darwin built on Lamarck’s idea Evolution based on natural selection

 Gregor Mendel Experimented with pea plants Trying to understand how characteristics passed between generations He discovered a gene  Founded the study of Genetics

 Fighting Diseases 1796 Edward Jenner developed smallpox vaccine Louis Pasteur recognized the impact of bacteria causing disease  Showed bacteria could be killed  New Approaches to Surgery Sir James Simpson discovered chloroform Joseph Lister introduced methods to sterilize instruments

 Atomic theory – all matter is made up of atoms John Dalton provided proof  Wilhelm K. Roentgen discovered X rays  Marie Curie and Pierre Curie discovered radium  Max Planck theorized that energy is released in units called quanta

 People started using scientific method to study human behavior Auguste Comte believed there was a set of laws to human behavior Father of sociology  Sociology – study of human behavior in groups  Psychology – study of human behavior in individuals  Ivan Pavlov – noted that human actions are unconscious  Sigmund Freud – father of psychoanalysis